SMITH : NOMENCLATURE OF CERTAIN GENERA. ■ 337 



as, in his general remarks on Faludina, as I have already ob- 

 served, he quotes F. acuta (\)K^'^)=^{veutrosa Montagu fide 

 Jeffreys) as the typical species, so that we can for ourselves 

 limit his genus to that and allied species. 



Jeffreys states that ' the estuarine or brackish-water species 

 of Hydrobia were formed by Professor D'Orbigny into another 

 genus, which he called Paludestritia ; and these also constitute 

 the genus Paludhiella of Pfeiffer and Loven.' 



I do not know from what source Jeffreys may have derived 

 his information, but it is not a fact that D'Orbigny included only 

 brackish-water forms in his genus, for of the ten species de- 

 scribed in the ' Voyage dans I'Amerique Me'ridionale,' seve?i 

 are from fresh and three only from brackish-water. 



In the next place I would point out that PahidineUa of 

 Pfeiffer^ is totally distinct from Paludestritia and belongs to 

 the Assitiiiniidce, having the eyes on the upper surface at the 

 base of the tentacles, and being more or less amphibious. 



VITREA vice ZONITES. 



The species which I propose to place in the genus Vitrea 

 of Fitzinger are generally spoken of by British Conchologists 

 as species of Zonites. None of them however agree with the 

 typical form of that genus, Z. algirus. This species is a large 

 coarsely striated shell and without the beautiful gloss so char- 

 acteristic of the typical Vitreie. But the chief difference which 

 distinguishes Vitrea from Zonites occurs in the radula, that of the 

 latter genus much more closely resembling that of ^^//.v proper, 

 than that of Vitrea, or Hyaliuia as this group is usually called 

 by most Continental and American writers. 



It will be seen from the following synonymy that the name 

 Hyaliuia and its modifications cannot be adopted for these 

 species, as it has been employed in various senses, and has also 

 been used for genera of Lepidoptera (Hyalina 1866) and Reptiles 

 (Hyalinus 1820), 



I Wiegmann's Archiv, f, Naturgesch., 1841, p, 227, 



